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7 APPLICATION INSTRUCTIONS
7.12 Special Function Instructions
Natural logarithm operation on floating-point data (single
precision)
LOG(P)
*1 Applicable for the Universal model QCPU, LCPU.
• Returns the natural logarithm of the value designated by (S) taking (e) as base, and stores operation results at device
designated by (D).
• Only positive values can be designated by (S). (Operation cannot be performed on negative numbers.)
• When an input value is set using a programming tool, a rounding error may occur. For precautions, refer to Page 89
Precautions.
• In any of the following cases, an operation error occurs, the error flag (SM0) turns ON, and an error code is stored into SD0.
*2 There are CPU modules that will not result in an operation error if -0 is specified. For details, refer to Page 87 Using single/double-
precision real number data.
• Basic model QCPU: The serial number (first five digits) is "04122" or later.
(S): Data of which the natural logarithm is obtained or head number of the devices where the data is stored (real number)
(D): Head number of the devices where the operation result will be stored (real number)
Setting
data
Internal device R, ZR J\ U\G Zn Constant
E
Others
Bit Word Bit Word
(S)
*1
(D)
*1
Error
code
Error details Q00J/
Q00/
Q01
QnH QnPH QnPRH QnU LCPU
4100 The value specified in (S) is negative.
The value specified in (S) is 0.
The specified device value is -0.
*2
4140 The specified device value is not within the following range:
0, 2
-126
| Specified device value | <2
128
The specified device value is -0, unnormalized number, nonnumeric, and .
4141 The operation result exceeds the following range.
(when an overflow occurs)
|Operation result| < 2
128
Basic
Process
High
performance
Redundant
Universal
LCPU
Ver.
Command
Command
LOGP
LOG
LOGP
LOG
S
D
S D
32-bit floating-point
real number
( )
32-bit floating-point
real number
+1 +1
S DS D
log
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